To a large extent, recent research and development on battery technology has involved work on various versions of lithium-ion systems, and has been focused on small- to medium-scale applications, such as portable electronics and vehicle propulsion. Much less attention has been given to energy storage problems related to the large scale electrical power grid, despite costly transient outages, a rapidly growing need for frequency regulation, and the necessity for load balancing in concert with the integration of intermittent energy sources such as solar and wind. Instead of emphasizing large values of energy density and specific energy, these grid-scale energy storage applications demand high durability (e.g., long cycle life), high short term power output (e.g., high rate), and low cost.
Current solutions to address short term, high power requirements include traditional lead-acid batteries and certain advanced battery technologies. However, lead-acid batteries have insufficient cycle life and typically cannot withstand deep discharge. Common metal hydride/nickel batteries, which have excellent cycle life, are considered to be too expensive for use on a large scale, as are the sodium/sulfur and lithium-ion systems. In addition, these battery technologies typically show significant voltage hysteresis, and thus have reduced round-trip energy efficiencies when operated at high rates.
It is against this background that a need arose to develop the electrode materials and related methods and systems described herein.